The bonding, shaping, forming, consolidating or co-consolidating of layers of thermoplastic material, a workpiece, into various composite products is generally effected through the concurrent application of heat and pressure. Known devices to apply such heat and pressure may take the form of upper and lower platens for receiving the workpiece therebetween. The platens are provided with mechanisms to apply pressure to opposite sides of the workpiece and with electrical resistance elements to concurrently apply heat to the workpiece.
Various approaches are disclosed in the literature to improve the efficiency of heated platen presses. By way of example, note U.S. Pat. No. 3,964,958 to Johnson. According to that disclosure, at least one surface having a diaphragm is positioned adjacent to a mating support surface. The diaphragm and support surface are located in opposed relationship with respect to each other. Layers of material to be adhesively bonded therebetween are positioned in a pressure chamber between the diaphragm and the mating surface. The process indicates bonding of two materials with adhesive film. The pressure in the chamber is raised above the ambient pressure to thereby cause a deflection of the diaphragm. Either the support surface or the pressure chamber, or both, is moved towards the other causing contact between the deflected diaphragm and the support surface with the layers of material therebetween. As the relative movement continues and the pressure increases, heat is applied by electrical resistance elements. The material will thus be bonded and shaped into the final composite product by the effects of the heat and the pressure.
In U.S. Pat. No. 3,964,958 to Johnson, the use of Kapton is disclosed as a diaphragm material while U.S. Pat. No. 4,273,604 to Johnson discloses Kapton in the layer of a diaphragm, such diaphragm comprising a Kapton layer, bonding layers, middle layers and encapsulating layers.
Although many such advances are noteworthy to one extent or another, none achieves the objectives of an efficient, reliable, inexpensive, convenient to use hot platen presses designed for the efficient application of high thermal energy and pressure applied through a diaphragm.
As illustrated by the great number of prior patents and commercial devices, efforts are continuously being made in an attempt to improve hot platen presses and tooling to render them more efficient, reliable, inexpensive and convenient to use. None of these previous efforts, however, provides the benefits attendant with the present invention. Additionally, hot platen presses and tooling of the prior art do not suggest the present inventive combination of component elements arranged and configured as disclosed and claimed herein. The present invention achieves its intended purposes, objects and advantages over the prior art devices through a new, useful and unobvious combination of method steps and component elements, with the use of a minimum number of functioning parts, at a reasonable cost to manufacture, and by employing only readily available materials.
It is a general object of this invention to shape and form layers of thermoplastic or thermosetting materials with an improved polyimide diaphragm capable of sustaining high temperatures.
It is a further general object of the invention to shape and form improved composite products by consolidating and co-consolidating layers of thermoplastic or thermosetting material, through the application of high temperatures, using a stretchable diaphragm of Kapton, Upilex or equivalent film.
It is a specific object of this invention to provide an improved apparatus for shaping, forming, consolidating or co-consolidating a workpiece formed of layers of thermoplastic or thermosetting composite material into a final composite product including upper and lower supports; an upper polyimide sheet beneath the upper support and adapted to receive the workpiece therebeneath; means for applying high heat to opposite sides of the supports, the sheet and the workpiece; and means for applying high pressure to the upper face of the sheet and one side of the workpiece and for applying vacuum pressure to the other side of the workpiece for shaping and forming the workpiece into the final composite product.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.